1. Field of the Invention
The invention relates to a method for bead seating a tubeless tire onto a rim and an apparatus for the same.
2. Description of the Related Art
While tubeless tires provide significant advantages over the tube-type, it is extremely difficult to seat the bead of the tire on the rim. This difficulty creates a special problem when trying to change a tire on the road, far from the customary equipment used to seat the tire.
One solution to the problem had been the introduction of ether inside the tire. The ether is the ignited and the resulting explosion often will seat the bead of the tire on the rim of the tire. Of course, determining the precise amount of ether necessary to seat the tire without potential injury to the operator is often difficult to determine. Factors such as the volume of the tire, the relative humidity in the air, ambient breeze, volume of ether are virtually impossible for the operator to calculate in order to be reasonably certain that sufficient ether is being used. However, if too much ether, again virtually impossible to consistently determine, is used, then a dangerous explosion is possible. Although extremely dangerous and despite the warning by every tire manufacturer that this procedure should not be used, this method is still being employed even though a number of deaths and serious injury result each year.
Another solution, which is best described as mechanical, although it may include some pneumatic elements, relies on the use of flexible straps or segmented hoops which squeeze along the circumference of the tire and thereby force the bead upward toward the bead seating surface. These mechanical devices are not conducive to being portable and require a substantial amount of time in the preparation of the equipment prior to the inflation process.
Still another solution is a class of pneumatic tools, which utilize a source of compressed air to impart momentum to the bead and inject air into the tire, thereby initiating a progressive bead seating process. While these tools are substantial improvement over the above-described apparatus, this type of design still presents problems and, as yet, no pneumatic tool has been universally adopted or totally eliminated the practice of using ether.
U.S. Pat. No. 3,866,654, issued to Duquesne on Feb. 18, 1975, discloses a portable device for inflating tubeless tires that utilizes a source of compressed air stored within a tank which directly supplies an injection nozzle through a long flexible hose. A complicated valve is used for releasing the air stored within a portable tank to control the airflow. The device is expensive to construct, especially due to its complicated valve assembly and cannot release enough air in a sufficiently short period of time so that the bead of the tire will be forced against the rim to properly seat the bead. The inadequacy of this device to meet tire bead seating requirements is primarily due to its cumbersome valve as well as the use of a relatively long flexible standard compressed air hose.
U.S. Pat. No. 5,042,547, issued to Van De Sype on Aug. 27, 1991, discloses a tire bead seating device having multiple air injection nozzles. Four are depicted which direct air from a portable tank. Van De Sype recognized the need for using a simple valve, a ball valve, that permits faster release of the air than was achievable with Duquesne's disclosed valve. However, Van De Sype defeated any advantage gained by the use of the ball valve by requiring multiple flexible long flexible lines having small nozzles. This arrangement substantially increases the airflow resistance downstream of the ball valve, thus correspondingly slowing the rise time of the air released against the bead of the tire and subsequently, reducing the impact on the bead of the tire.
U.S. Pat. No. 5,072,764, issued to Ochoa on Dec. 17, 1991, discloses, as did Van De Sype, a bead seating apparatus that utilizes a hand-operated valve, preferably a ball-type valve, to release a charge of air from a portable storage tank. However, Ochoa, while recognizing the need for a very fast discharge of air from the storage tank, failed to recognize that his nozzle is unnecessarily restricting airflow. Ochoa teaches the use of a nozzle having a discharge area that is less than the cross-sectional area of the discharge barrel. Ochoa also teaches away from the use of large diameter discharge barrels, that is, discharge barrels having an opening larger than 20.4 square centimeters. Ochoa incorrectly states that larger dimensions of discharge barrels tend to cause the discharge impulse of air to impart an undesirably large quantity of momentum to the sidewall of the tire, thereby introducing undesired components into the motion of the bead of the tire. Consequently, much of the advantage gained by the use of a short, rigid, discharge short discharge barrel is lost. Ochoa failed to recognized that the time its takes for the ball valve to be moved from the fully closed to the fully opened position retards the rise time of the pulse of air, thus reducing the effectiveness of the apparatus.
An improvement on the Ochoa device is a tire bead seating apparatus that was manufactured by the BEAD SEATER Corporation. This device also featured a portable tank, a ball-type valve as taught by Van De Sype, Ochoa and a short, rigid discharge barrel as disclosed by Ochoa. However, the BEAD SEATER apparatus provided a unique fan-shaped nozzle having a radius that was dimensioned to correspond to the rim of the tire and had a discharge area that was always greater than cross-sectional area of the discharge barrel. While the nozzle as well as the use of discharge barrel larger than taught by Ochoa resulted in substantially improves performance over its predecessors. However, this device was still limited by the use of the ball-type valve.
U.S. Pat. No. 5,456,302, issued to Demers on Oct. 10, 1995, discloses a tire bead seating apparatus that eliminates the use of discharge barrel and its corresponding valve. This results in the pulse of air having a substantially faster pressure rise time than is found with above-referenced devices. This device makes use of piston that is releasably sealed against the outlet of the portable tank such that the piston is held against the tank outlet by having an air pressure that is higher on the side away from the outlet than is found on the side adjacent to the outlet. Once the air is released on the side of the piston away from the outlet via a quick release valve, the piston moves away from the outlet of the tank, allowing the air inside the tank to be released. The air flows from the tank and is immediately discharged out the discharge nozzle.
This device is substantially more effective than previous attempts due to the substantial faster response time and the further reduction in airflow resistance. However, the design suffers from having a higher cost of manufacture than the Ochoa or BEAD SEATER devices. By having an integral nozzle, this device exhibits an appreciable kickback, especially if the tank is filled to a higher pressure such as 100 lbs/in.sup.2. Further, the device is particularly sensitive to even small leaks since the volume of air on side of the piston away from tank outlet is very small compared to the volume of air in the tank. Once a small amount of air leaks, the pressure differential across the piston can easily be lost, thus preventing the piston from releasing sufficiently quickly to produce the desired very fast pressure rise time of air that is necessary to efficiently seat the bead of the tire.
A device that is inexpensive to produce, relatively insensitive to leaks, substantially reduces or eliminates kickback, and still provides the extremely fast release of air from the reservoir tank is not found in the prior art.